[PATCH v5 06/27] irq_domain/powerpc: eliminate irq_map; use irq_alloc_desc() instead

[Russell King - ARM Linux]

On Mon, Apr 02, 2012 at 02:28:48PM -0600, Grant Likely wrote:
> On Mon, 02 Apr 2012 18:29:15 +0200, Andreas Schwab <schwab at linux-m68k.org> wrote:
> > Andreas Schwab <schwab at linux-m68k.org> writes:
> > 
> > > Grant Likely <grant.likely at secretlab.ca> writes:
> > >
> > >> This patch drops the powerpc-specific irq_map table and replaces it with
> > >> directly using the irq_alloc_desc()/irq_free_desc() interfaces for allocating
> > >> and freeing irq_desc structures.
> > >
> > > This breaks irqs on PowerMac G5.  I see lost irq errors from the sata
> > > driver.
> > 
> > When I revert a09b659cd68c10ec6a30cb91ebd2c327fcd5bfe5 ("genirq: Fix
> > long-term regression in genirq irq_set_irq_type() handling") on top of
> > 3.4-rc1 the sata irq errors disappear, but I see a lot of spurious
> > interrupts.  Also the X server is broken somehow, though I don't know
> > whether that is related or a different bug.
> 
> That change is:
> 
> @@ -61,8 +61,7 @@ int irq_set_irq_type(unsigned int irq, unsigned int type)
>                 return -EINVAL;
>  
>         type &= IRQ_TYPE_SENSE_MASK;
> -       if (type != IRQ_TYPE_NONE)
> -               ret = __irq_set_trigger(desc, irq, type);
> +       ret = __irq_set_trigger(desc, irq, type);
>         irq_put_desc_busunlock(desc, flags);
>         return ret;
> 
> So presumably irq_set_irq_type() is getting called with type ==
> IRQ_TYPE_NONE.  From Russell's description, presumably that would mean
> the G5 sata driver isn't setting the correct type for the interrupt,
> but I have *no* idea how that intersects with the change removing the
> powerpc irq map.

Well, presumably someone is calling irq_set_irq_type() asking explicitly
for IRQ_TYPE_NONE.  The code will now (as it always used to before David's
change) do exactly what you ask this to: it will ask the type to be set
to none.

If you don't want to set the type to none, don't call the interface asking
for that to happen.